Viscous products are known on the market since they give to the consumer a gratifying and stable product quality. However, such products are often graded by the consumer as being heavy. One way to improve the acceptance of these products by the consumer is by incorporating air or gas into such products since this gives more lightness and delight to the consumer during consumption of these viscous products.
However, technically, it is not a trivial task to incorporate air or gas into viscous food matrices. It is well known that above a certain viscosity, it is very difficult to incorporate air in a significant amount. Most of the air added to the product during the whipping or foaming step is not incorporated into the viscous product and lost (Blow-by). Moreover, the air is incorporated in form of large, polydisperse air bubbles into the viscous matrix. The bubble mean size, size distribution and bubble interface composition cannot be easily controlled, and the quality of the final produced product, i.e., stability over time and sensory attributes, cannot be assured.
Classically, in order to make and stabilize the foamed product, a stabilizer system consisting of an emulsifier system and a viscosifying agent has to be added to the aqueous bulk phase prior to the foaming step. The main drawback of this is, however, the limitation of making foams out of aqueous phases which are viscous due to the significant decrease of the diffusion rate of the emulsifier system from the viscous bulk phase to the bubble interface during the foaming process resulting in a unacceptable final product quality (broad gas bubble distribution and inhomogeneous distribution of the entrained gas) and low shelf stability. So far the control and design of the texture of foamed products is mainly achieved by adding a viscosifying agent to the food matrix prior to the foaming step, leading to a low product quality if the viscosity of the liquid bulk phase is too high.
In order to make stable foamed products, specific emulsifier/stabilizer systems have to be added prior to the foaming step. For instance, U.S. Pat No. 6,368,652 B1 describes food products including whippable products which are stabilized by a specific surfactant combination, i.e., mainly consisting of a non-ionic surfactant and a minor amount of an ionic co-surfactant. The non-ionic surfactant is selected from monoglycerides while the ionic co-surfactant may be alkali salts of lactylated fatty acids, citric acid esters, succinated esters and diacetyl tartaric acid ester of monoglycerides. The ionic co-surfactants are used to swell the monoglyceride based lamellar liquid mesophases, i.e., to solubilize a large quantity of water into the inter-planar water layers of the bilayers making this mixture suitable as a structuring agent of the aqueous phase, fat replacer or foam control agent.
EP 1 366 670 A1 describes a gas containing desert and a method for preparation thereof in which the gas bubbles are stabilized by partially coalesced fat. Aerated food products, in which the gas bubbles are stabilized by partially coalesced fat, are based on fat-containing recipes, since partially coalesced fats are known to stabilize gas/air bubbles and foamed products, such as ice or whipped creams. However, such fat-based aerated products show limited stability during shelf-life. The reason of this is related to the insufficient stabilization of the air bubble structure against Ostwald ripening, coalescence or creaming leading to an increase in the bubble size, bubble size distribution and change in interface composition.
It is object of the invention to provide a technology to incorporate air or gas into viscous food matrices enabling a better control and stabilization of the air/liquid interface during the aeration process.
It is another object of the invention to provide shelf-stable viscous and indulgent food products having a controllable air bubble structure, i.e., a stable air/liquid (bubble) interface and an improved shelf-life.